Thin-film transistor sensor and method of manufacturing the TFT sensor

Abstract

According to an aspect of the present invention, there is provided a thin-film transistor (TFT) sensor, including a bottom gate electrode on a substrate, an insulation layer on the bottom gate electrode, an active layer in a donut shape on the insulation layer, the active layer including a channel through which a current generated by a charged body flows, an etch stop layer on the active layer, the etch stop layer including a first contact hole and a second contact hole, and a source electrode and a drain electrode burying the first and second contact holes, the source and drain electrodes being disposed on the etch stop layer so as to face each other.

What is claimed is: 
     
       1. A thin-film transistor (TFT) sensor, comprising:
 a bottom gate electrode on a substrate; 
 an insulation layer on the bottom gate electrode; 
 an active layer in a donut shape on the insulation layer, the active layer including a first channel and a second channel through which current generated by a charged body flows and including a hole for separation of the first channel and the second channel; 
 an etch stop layer on the active layer, the etch stop layer including a first contact hole and a second contact hole, and including a middle portion that overlaps the hole for separation of the first channel and the second channel; 
 a source electrode and a drain electrode burying the first contact hole and the second contact holes, the source electrode and the drain electrodes being symmetrically disposed on a pair of first opposite regions of the middle portion of the etch stop layer so as to face each other; 
 a first top gate electrode and a second top gate electrode that are symmetrically disposed on a pair of second opposite regions of the middle portion of the etch stop layer so as to face each other, the first top gate electrode and the second top gate electrode being spaced apart from each other and controlling flow of the current through the first channel and the second channels, respectively, 
 wherein each of the first opposite regions does not overlap with each of the second opposite regions; and 
 wherein changes in amounts of the currents flowing in the first channel and the second channels occur based on movement of the charged body relative to the first top gate electrode and the second top gate electrodes, and correspond to a touch direction and a touch intensity of the charged body. 
 
     
     
       2. The TFT sensor as claimed in  claim 1 , wherein:
 the donut shape is generally a square or rectangle, and 
 the first contact hole and the second contact holes are disposed on corner areas of the active layer so as to diagonally face each other. 
 
     
     
       3. The TFT sensor as claimed in  claim 1 , wherein the first contact hole and the second contact holes are formed on edges of the active layer so as to face each other. 
     
     
       4. The TFT sensor as claimed in  claim 1 , wherein the first top gate electrode and the second top gate electrodes are on a same level as the source electrode and the drain electrodes without physically contacting the source electrode and the drain electrode. 
     
     
       5. The TFT sensor as claimed in  claim 4 , wherein a direction of the current flowing in the first channel and the second channel is controlled by applying a periodically-swinging voltage to the first top gate electrode and the second top gate electrode. 
     
     
       6. The TFT sensor as claimed in  claim 1 , wherein the hole is at the center of the active layer, and the first channel and the second channels are arranged on different sides of the hole. 
     
     
       7. The TFT sensor as claimed in  claim 1 , wherein the active layer includes an oxide semiconductor. 
     
     
       8. The TFT sensor as claimed in  claim 1 , wherein:
 the active layer has four outer edges, 
 the first contact hole and the second contact holes are symmetrically disposed on two of the four outer edges, facing each other, and 
 the source electrode and the drain electrode are symmetrically disposed on the two of the four outer edges, and the first top gate electrode and the second top gate electrode are symmetrically disposed on two remaining edges of the four outer edges without physically contacting the source electrode and the drain electrode. 
 
     
     
       9. The TFT sensor as claimed in  claim 1 , wherein the donut shape is generally a square or rectangle. 
     
     
       10. The TFT sensor as claimed in  claim 1 , wherein the touch direction is determined from a difference between the amounts of the currents flowing through the first channel and the second channels by the first top gate electrode and the second top gate electrodes over time, and the touch intensity is determined from the amounts of the currents flowing through the first channel and the second channels by the first and second top gate electrodes. 
     
     
       11. The TFT sensor as claimed in  claim 1 , wherein the bottom gate electrode, the first top gate electrode, and the second top gate electrode are disconnected from one another. 
     
     
       12. A thin-film transistor (TFT) sensor, comprising:
 a bottom gate electrode on a substrate; 
 an insulation layer on the bottom gate electrode; 
 an active layer in a donut shape on the insulation layer, the active layer including a hole for channel separation at the center of the active layer, and wherein the donut shape is generally a square or rectangle having four outer corners; 
 an etch stop layer on the active layer, the etch stop layer including a first contact hole and a second contact hole, the first contact hole and the second contact hole being symmetrically disposed on two of the four outer corners, diagonally facing each other; and 
 an electrode layer on the etch stop layer corresponding to areas of edges of the active layer, the electrode layer including a source electrode and a drain electrode that bury the first contact hole and the second contact hole and are symmetrically disposed on the two of the four outer corners, and including a first top gate electrode and a second top gate electrode that are symmetrically disposed on two remaining corners of the four outer corners without physically contacting the source electrode and the drain electrode. 
 
     
     
       13. The TFT sensor as claimed in  claim 12 , wherein a direction of current flowing in separate channels is controlled by applying a periodically-swinging voltage to the first top gate electrode and the second top gate electrode. 
     
     
       14. The TFT sensor as claimed in  claim 12 , wherein the active layer includes an oxide semiconductor. 
     
     
       15. The TFT sensor as claimed in  claim 14 , wherein the active layer oxide semiconductor includes at least one material selected from the group of In, Ga, Zn, Sn, Sb, Ge, Hf, Al, and As. 
     
     
       16. A thin-film transistor (TFT) sensor array comprising:
 TFT sensors arranged by rotating each of the TFT sensors by a predetermined angle from corresponding adjacent ones of the TFT sensors; 
 wherein each of the TFT sensors includes: 
 a bottom gate electrode on a substrate; 
 an insulation layer on the bottom gate electrode; 
 an active layer in a donut shape on the insulation layer, the active layer including a hole for channel separation at the center of the active layer, and wherein the donut shape is generally a square or rectangle having four outer corners; 
 an etch stop layer on the active layer, the etch stop layer including a first contact hole and a second contact hole, the first contact hole and the second contact holes being symmetrically disposed on two of the four outer corners, diagonally facing each other; 
 a source electrode and a drain electrode burying the first contact hole and the second contact holes, the source electrode and the drain electrodes being symmetrically disposed on the two of the four outer corners; and 
 a first top gate electrode and a second top gate electrode being symmetrically disposed on two remaining corners of the four outer corners without physically contacting the source electrode and the drain electrode. 
 
     
     
       17. The TFT sensor array as claimed in  claim 16 , comprising four of the TFT sensors, wherein the predetermined angle is 90 degrees.